This invention relates generally to the field of construction, and more particularly to a method and apparatus for forming a trench or catch basin void.
Historically, mankind has been using trench drains since the dawn of time. The Romans used them to deliver water to cities for drinking and bathing and to farm lands for irrigation. Trench drains have also been used to collect runoff and channel it to other locations preventing flooding. In recent times trench drains have been used as secondary containment systems preventing chemical spills from escaping into the environment.
Most trench drains are formed in place using plywood to make both a bottom form, and side forms, which must be removed after the concrete has set. It is time consuming and requires a carpenter to build the forms. This type of trench also requires a waterstop in the keyway joint where the walls and floor of the trench join. Styrofoam forms are the latest products to enter the market. They are comprised of solid foam that is cut into the shape of a trench drain, use elongated steel members and supports to hold them prior to concrete encasement. Such a system was disclosed in U.S. Pat. No. 5,478,169. They are comprised of solid foam forms that are cut to the shape of the basin desired, and use steel frames and supports to suspend them prior to concrete encasement. Foam forms are expensive to ship due to large bulk and no weight. They are susceptible to damage in transit. Compared to wood forming techniques they are expensive. Styrofoam is flammable and can give off toxic gases. It breaks up into small light pieces during deformation and can be scattered by the lightest wind, littering the landscape. Landfills do not like to take styrofoam because it will not decompose and takes up excessive space.
Historically most catch basins are made of precast concrete, which are extremely bulky and require heavy equipment to lower them into place. The outlet holes must be cased in exact locations to match the elevations required on each specific jobsite, and the size of pipe specified. Because of their weights, they can be dangerous during placement and can cause serious injury or death. They must be transported by tractor trailers to the jobsites because of their bulk. Another method is to form the catch basin in place using plywood to make both a bottom form and side forms. This requires a carpenter to cut and build the forms. This is both time consuming and costly in labor and materials. Similar use of styrofoam as described above has been employed to form catch basins as well.